There's a flaw in your argument. People choose to train putbulls for violence because of their appearance, tenacity, and strength. Therefore the violence stats. will reflect that. Without evidence of a GENETIC factor. Your assertion is merely based on popularity.
Idk if you know this, but the "Pit Bulls have the worrier gene" meme was heavily used by the Far Right to Red Pill people on Race Realism e.g. "Look at this violent dog breed. It's just in their genes." leads to "Wow! These Black people sure are violent. I wonder why that is?"